1. Field of the Invention
The present invention generally relates to the field of semiconductors. More particularly, the invention relates to transistor semiconductors structures.
2. Background Art
Various types of MOS (Metal Oxide Semiconductor) transistors, such as Lateral Diffusion Metal Oxide Semiconductor (LDMOS) transistors, can be utilized as power transistors in high voltage switches and power amplifiers in cell phones and other wireless communication devices, as well as other types of applications that require a high power transistor. In a MOS transistor, such as an LDMOS power transistor, the source region and the body region of the transistor are typically tied together to prevent a parasitic bipolar transistor from turning on and possibly destroying the power transistor, where the base, emitter, and collector of parasitic bipolar transistors are formed by the body region, source region, and drain region of MOS transistors, respectively. To effectively couple the source region to the body region of the transistor, a body tie region is typically situated close to the source region to reduce resistance. However, the body tie region can undesirably increase the area or footprint of the MOS transistor in a semiconductor die.
In a conventional LDMOS transistor, for example, a source region can be situated between a body tie region and a first side of a gate and a drain region can be spaced apart from a second side of the gate by a lightly doped region. In the conventional LDMOS transistor, the body tie region and the source region can be situated in a body region. A body tie contact on the body tie region and a source contact on the source region can be electrically connected so as to cause a potential of the source region to be substantially equal to a potential of the body region, thereby preventing the aforementioned parasitic bipolar transistor from turning on and possibly destroying the conventional LDMOS transistor. However, the body tie region can undesirably increase the area (i.e. the footprint) of the conventional LDMOS transistor on the semiconductor die.